removable devices auto umounting

Patrick C pcloches at
Thu Mar 20 02:08:16 PDT 2008

What about a "Safely Remove Hardware"-style icon on your desktop,
which could simply run a script to unmount (with force if the user has
it open somewhere).


On 20/03/2008, Roland Smith <rsmith at> wrote:
> On Thu, Mar 20, 2008 at 11:55:32AM +1000, Da Rock wrote:
>  > I'm just looking into the removable device issue for freebsd. I can see
>  > its easy enough to auto mount a removable device (although I could use
>  > some help getting sd/xd devices working with my card reader), but the
>  > removal seems to come unstuck.
>  >
>  > I have some barely literates on my systems, so I do need to work this
>  > out. Is it possible to use a forced umount to do this? What are the
>  > options here?
> In short, no. Removal of a USB device would be forwarded to devd(8). But
>  since the device is no longer there at that moment, you cannot unmount
>  it anymore. You might get a nice kernel panic for your efforts, though. ;-)
>  The FreeBSD disk subsystem was simple not written with removable devices
>  in mind, because they didn't exist back then. Until that code is fixed
>  (which is hard) you _have_ to unmount before you pull the device out.
>  One (not bullet-proof) workaround might be to use the automounter
>  [amd(8)], and have it unmount very quickly after they stop being
>  active. This requires setting both the 'cache_duration' and
>  'dismount_interval' options in amd.conf(5) to very low values.
>  Roland
> --
>  R.F.Smith                         
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